Valhall Corrosion Events and ManagementLearning Pack

EldarLarsen,HeadofOperations,BPNorway.

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ValhallCorrosion Events - Summary

Summary

HydrocarbonleakHIPOon6thMarch2009causedbyMicrobialInducedCorrosion(MIC)

resultedincrudeandgasleak,FirstAidIncident,emergencyplantshutdown&muster.

Valhalleventuallyshutdownfor10weeksforcorrosioninspectionandrepairs.

duringwhichthreefurtherincidencesofMICand44anomaliesidentified.

Major Lessons

Behaviours of MIC were misunderstood

AreasofhighflowratewerepreviouslythoughtunlikelytoexperienceMIC,thisassumptionfailedtoidentifyinternalpipeworkscalingcanprovideenvironmentforMICactivity.

Inadequate application of hazard Recognition, risk awareness and control of work.

TheinitialinspectionroutinewasinappropriateanddirectlyledtoexposureoftheindividualandtheresultantFAI.

15specificimprovementopportunitiesidentifiedasaresultoftheincidentandplantinvestigations(7organisational,5workprocessand3performancemanagement).

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Microbial Induced CorrosionWhatisMIC?

MICisMicrobialInducedCorrosion.

MICofcarbonsteeltypicallymanifestsitselfaslocalisedcorrosionorpittingattackfollowingthedevelopmentofasurfacebiofilm.

Theanaerobicenvironmentsofoilandwatertransportpipeworkoftensupportthegrowthofbiofilms,whichalmostinvariablycontainsulphate-reducingbacteria(SRB),amajorcauseofMIC.

SRBcontainingbiofilms generateH2S.

H2SresultsinformationofIronsulphidewithinthebiofilm.

Ironsulphidesarecathodictobaresteelandcanhavetheeffectofgreatlyincreasingcorrosionatanodicsites.

WhydoesMICoccur?

MICcanoccurinallsystemsthatcontainwaterwithSRBs.

PredictionofcorrosionratesattributedtoMICisunreliable

uncertaintyoftheonsetoflocalizedcorrosion/pitting,whether itproceedsataconstantrate.

ParametersthatcaninfluenceMICincludepH,temperature,nutrition,velocityoffluids,presenceofdeposits.

MICismorelikelytooccuratlocationswithlowfluidvelocity suchasindeadlegs,underdeposits,scale.

AllmetalsaresusceptibletoMIC.Carbonsteelshavegenerallybeenfoundtobemostsusceptible.

MICmitigationreliesoneffectivebiocidedosingregimes.

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Reference - Valhall Timeline

1982

Valhallstart

production,

Incl.Jet

washing

separators

using sea-

water.By

mid-90s

using mainly

produced

water

1998

NewMetering

Skidinstalled.

Smallbore

pipeworknot

commissioned

inWorkmate

1999RBIAnalysisperformedMICinternalcorrosionnotsufficiently

identifiedasathreat.

2000

Inspection

scheme

constructed

which

identified

external

inspectionof

Liquids

metering

packageasa

whole

2004-2006

Chemical

cleaningof

fastloopto

aid

calibration

duetoscale

buildup

Ongoing

Biocide

treatmentof

Sulphate

Reducing

Bacteria

(SRB)on

Produced

Water(PW)

system

ongoingand

working

2007

SRBs in2nd

stageseparator

0-460/ml

Sept 2007

Cor.Mngt.Health

Check:Valhall

Prod.Water

SulfateReducing

Bacteria(SRB)

contaminationas

ahighriskand

recommendsa

microbialauditby

microbial

specialist

06.Mar.2009

Leakin1

pipefast

loop

HIPO

02.Apr.2009

Upstream

skimmedoil

tank

17.Apr.2009

Leakin6

prod.water

pipe

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Reference - Valhall TimelineEvents and response:

6thMarch2009Meteringfastloop (F&G ESD). LimitedawarenessofMIC,deemedlowprobability.LimitedspotcheckingbyX-rayoutsidethe

fastloop.NoSDjustifiedbyresidualcorrosionrisk.Noadditionalresources.

2ndApril2009T-337pressureincrease (NoESD).

StartupafteracompressorincidentincreasedflarebackpressurewhichburstaMICinthe

producedwatersystem.

15days(6+9)shutdownlookingforMICwithEddycurrentandX-rayw.crewof3.

17thApril20096 producedwaterpipe (NoESD).

RestartattemptfailedwhenaMICburstintheprod.watersystem.Hadbeeninspectedinvery

closevicinity.Increasingrealizationofthecriticalityofadequateinspectionrigour.

10daysshutdown,100%inspectionofprod.watersystembyEddy currentandX-ray,extended

riskbasedapproach.Increasedoffshoreresources.

27thApril2009Condensatereturntoprod.watersystem.(F&G ESD).

Pipeburstduringstartupattempt.Containedhighlyvolatilecondensate.

Realizedtechnologygap.ChangedtoSLOFECscanningsuccessfully.

30+teamoffshore.Taskforceonshore.True100%inspectionbeyondproducedwater.RIB

revision.

1stJune2009Successfulrestart.

10weeksofproductionlossandseriousHSEincidents.

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Valhall Corrosion Event (March 6th 2009)Summary of first event.

Aseep orsweatingleakobservedcomingfromaninsulated1 carbonsteelpipewaspreparedforinspectionfollowingremovaloftheinsulation.

Thepipewasonthecrudeexportmeteringskidandcontainedamixtureofcrudeoilandgasat25barpressure.

Onremovalofinsulation,theleakwasobservednottooriginatefromtheflangeasoriginallyexpected.

Aninspectorexaminingthepipeinitiallyusedabladetoscrapeoffpaintattheleaksite.

Duringalatervisit,theinspectortouchedtheleaksitewithhisfingerandwassprayedinthefacewithoilunderpressure.

Duringhydrocarbonrelease,theholeenlargedto10mmdiameter.

ValhallwenttofullEmergencyShutdownandmuster.

Hydrocarbon leak on metering skid First Aid Incident Emergency Plant Shutdown

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Inherent Design

Plant Layout

Control, Alarm &

Shutdown system

Inspection (RBI) and Corrosion Management practices failed to identify and mitigate the internal corrosion threat/risk that led to the failureRBI assessment not updated to reflect changes to operating and/or process conditions

Maintenance

& Inspection

Learning from

the Past

Actions from 2007/2008 Health Checks to improve Biocide treatment and to conduct Microbial survey not completed

Force Inspection procedures inconsistent with requirements of HSE Directive for visual inspection

Operations

Procedures

Inspection Engineer delegated inspection task to NDT Technician.

Effective

Supervision /

Leadership

Training &

Competency

Failure to follow CoWand RBI procedures

Work Control

Inadequate Hazard Recognition and Risk Awareness job treated as routine and Level 2 work permit.CoW - Failure to isolate energy source prior to workCoW - Failure to comply with requirements for Visual Inspection

Support to Next

of Kin & Injured

Relief and

Blowdown

system

Audit & Self

Regulation

No apparent MoC for chemical treatment of Fast Loop line.1 line not identified on risk-based inspection schedule

Management

of Change

Active & Passive

Fire Protection

Escape /

Access

Rescue &

Recovery

HAZARDHydrocarbon Inventory at

25bar in Fast Loop line

Investigation &

Lessons Learned

HAZARDREALISATION

Loss of containment

First Aid injury & HiPo

Hazard Barrier Diagram

Heirarchy of control Bias towards hardware/inherent safety & reducing the scope for human error multi barrier defence

Four Point Check not used.

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Valhall Corrosion Event (April 2nd 2009)Summary of second event.

AleakintheProducedWaterSystemfollowed

agascompressionupset.Areaisolated&

upstreamvesseldrained.

25mmholefoundindrainline.

Areasoflowflowanddead-legswereidentified

andinspected.6furtherMICincidents

observed.

Investigationinitiatedtoensureappropriate

analysisandresponsepriortorestart.

Managementverificationofprocessmitigations

andcorrosionmapping&repaireffort.

Targeted inspected discovers further incidence of MIC

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Valhall MIC Response The third event: Defining the Scope of Work

ProducedWateridentifiedasbeingthemain

hostofSulphate ReducingBacterias (SRBs)

Consideredpotentialcontaminationofother

systemsvsHCleakrisks.

ScopeagreedbyOps,ProcessTA,Corrosion

MgmtTA,Inspection&CMContractor.

ProducedWaterSystemwas100%inspected.

RiskBasedHotspot Execution Waterwetted

surfaceseg Lowspots,Sumps,Deadlegs etc.

Wasteinjectionondrillingplatform(DP).

Wellsystems,confinedtoslurrylines.

CrudeOilprocessingincludingthe

meteringsystem.

ClosedDrainsSystem.

Oil Return from PW Flash Drum to Oil Return tankOrientation of defect; 9 oclock position on vertical pipe

Unpredicted nature and location of corrosion required a new approach to

immediate reaction inspection.

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Leakin6producedwaterhighflowpipework

A8mmholewasdiscoveredduringpreparationforplantrestartfollowinginspectionprogramtriggeredtwogasdetectors&ESD.

Critical Factor1

MicrobialinducedCorrosion(MiC)mechanismintheproducedwatersystem

CriticalFactor2

Inspection(RBI)andCorrosionManagementpracticesfailedtoidentifythecorrosionriskinhighlevel,highflowpipework

Targeted inspected discovers further incidence of MIC in high flow pipework

ValhallCorrosionEvent.Summaryofforthevent.

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Valhall MIC project Inspection

Extensiveinspectioneffortrequiredtoexecute

identifiedscope 30+strongteam.

SLOFECtechnologyused

Priority1scopeIdentified44anomalies

23MICRelated

21Non-MIC-related

19spoolsreplaced,5temporarilyrepaired&20

scheduledforongoinginspectionfollowingstart-up

AssuranceprocessesfollowedbyNogo/Go

verificationreviews

Priority2inspectionscopeidentifiedforpoststartup

inspection.

No.10 T-337Flangecorrosion

Following fresh focussed risk assessment an intense and prioritised

inspection programme was initiated.

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Lessons Learnt

Direct cause

CrosscontaminationofoilproductionsystemwithSRBviatheproducedwater

system.

Inadequateawareness,inspectionandmitigationasanalysisdidnotidentifyoil

systemasatriskfromSRBcorrosion.

Insufficientchemicalinjection(suchasbiocideandcorrosioninhibitor)and

samplingandanalysistocontrolmicrobialactivity.

AsaresultMICoccurredwithinoilsystems.

Underlying causes

Improvementopportunitiesidentifiedwithin:

Organization (7subcategorieswithrecommendations)

Work Processes (5subcategorieswithrecommendations)

Performance Management (3subcategorieswithrecommendations)